Project Summary/Abstract While the care of premature infants continues to improve survival for infants born at increasingly shorter gestational ages, there is no evidence that the rate of bronchopulmonary dysplasia (BPD), the most common chronic lung disease of prematurity, is significantly declining, leaving an overall growing population of children with substantial respiratory health impairment. Almost half of all school-aged children with BPD have asthma or asthma-like symptoms and more suffer long-term lung function abnormalities that put them on a trajectory of poor lung function in adulthood. Few studies have evaluated contributing factors to long-term respiratory mor- bidity, and, except smoking, there is an absence of data regarding post-neonatal intensive care unit (NICU) environmental influences. Air pollution and indoor respiratory irritants are known to cause respiratory symp- toms, decline in lung function, and are associated with healthcare utilization in several at-risk populations of children with chronic respiratory conditions, as well as, populations of healthy children. Therefore, identifying the impact these potentially-modifiable exposures have on the high rate of symptoms and lung function abnor- malities in this group is critically important to developing future interventions to improve the health of children with BPD. The overall objective of this study is to determine the contribution of indoor air quality and environmen- tal exposures in the home environment to respiratory morbidity in children with a history of BPD, the first step toward achieving the long-term research goal of producing targeted interventions to improve respiratory health in children with chronic lung diseases. The central hypothesis is that children with BPD suffer respiratory mor- bidity by exposure to air pollutants encountered inside the home environment, independent of allergens and other factors. This proposal details a five-year project to investigate the role of indoor environmental exposures on respiratory symptoms, and, separately, on lung function deficits in school-aged children with BPD. State-of-the- art measures of indoor air quality constituents will assess the relationship of nitrogen dioxide (NO2), particulate matter (PM2.5), as well as, concentrations of allergens (mold, mouse, cockroach, pet), endotoxin, air tempera- ture and humidity with concurrently measured respiratory symptoms and lung function in a well-characterized cohort of children with BPD. This research will identify specific harmful components of the indoor environment associated with respiratory morbidity and poor lung function in children with BPD, independent of neonatal BPD severity and other known epidemiologic risk factors. The impact of these findings will be to identify modi- fiable risk factors and identify future opportunities to test interventions that may improve the substantial respira- tory health burden suffered by this growing high-risk group of children with BPD throughout life.